SIEMENS
4/26
Siemens IC 10 · 2017
Contactors for Special Applications
SIRIUS 3RT26 contactors for capacitive loads (AC-6b), 3-pole
4
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Overview
Standards
IEC 60947-1, EN 60947-1,
IEC 60947-4-1, EN 60947-4-1,
IEC 60947-5-1, EN 60947-5-1,
IEC 60831-1, EN 60831-1,
IEC 61921, EN 61921
The 3RT26 contactors are suitable for use in any climate.
They are finger-safe according to IEC 60529.
Function
The 3RT26 contactors for capacitive loads (AC-6b) are special
versions of the 3RT20 contactors size S00, S0 and S2 which are
configured for switching banks of capacitors.
They are designed to convey the inrush current in such applica-
tions, and are weld-resistant in compliance with the technical
specifications.
The 3RT26 contactors are suitable for choked and unchoked ca-
pacitors. Besides switching power capacitors in reactive-current
compensation systems, they are also used to switch converters.
In the case of 3RT26 contactors, the precharging resistors are
an integral component of the contactor. The precharging resis-
tors are activated via leading auxiliary contacts before the main
contacts close. During switching, after attenuation of the peak
current, they are decoupled again. Attenuation of the inrush
current peaks also reduces interfering harmonics in the supply.
Notes:
Only switching onto discharged capacitors is permitted with
3RT26 contactors.
Manual operation for function tests is not permitted. The series
resistors must not be removed.
Auxiliary switches
The variance of unassigned auxiliary switches has been in-
creased; for available versions,
see "Selection and ordering
data", page 4/31
. Details of deviating versions are available on
request.
In sizes S00 and S0, the auxiliary switch block which is snapped
onto the capacitor contactor contains the three leading NO con-
tacts and one unassigned auxiliary contact. In addition, another
one (S00) or two (S0) unassigned auxiliary contacts are pro-
vided in the basic unit.
The fitting of auxiliary switches for 3RT26 contactors in sizes S00
and S0 of the respective version is not expandable. For size S2,
unassigned auxiliary switches are implemented by means of lat-
eral auxiliary switch blocks. More auxiliary switch blocks can be
mounted laterally corresponding to the 3RT20 contactors.
Devices with 2 NC contacts are now consistently available in all
power quantities.
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Technical specifications
More information
Technical specifications,
see
Manuals,
see
Type
3RT26
Size
S00 ... S2
Contact endurance of the main contacts
The characteristic curves show the contact endurance of the contactors
when switching capacitive loads (AC-6b) depending on the reactive
power
Q
N
and rated operational voltage.
The rated operational current
I
e
in accordance with utilization category
AC-6b (breaking of 1.35 times the rated operational current) is specified
for a contact service life of approximately 150 000 to 200 000 operating
cycles.
a
N
[kvar] / 400 V
AC-6b
[A]
2
4
6
8
2
10
0
4
6
8 10
1
2
4
6
8 10
2
10
+6
10
+5
10
+4
3RT2617
3RT2625
3RT2626
3RT2627
3RT2628
3RT2636
3RT2637
IC01_00386b
1,4
2,9
5,8
14
28
144
Reactive current
Electrical durability (operating cycles)
Reactive power Q
N
[kvar] / 400 V
© Siemens AG 2016